JPS61140038A - Fluorescent character display tube - Google Patents

Abstract

PURPOSE:To improve electrical conductivity of a bonding part by profitably employing an Au-Si eutectic method for die bonding for an IC chip of the captioned fluorescent character display tube having a COG structure. CONSTITUTION:A segment electrode 4 having a fluorescent layer, an IC chip 11 for driving path, and a pad part 5 for wire bonding are provided on glass substrate 1. A metal supporter 20 is formed by etching copal metal and subjecting an IC chip mount part to Au plating. Thereafter, it is heated in inactive gas to join the IC chip 11 with the metal supporter by making use of an Au-Si eutectic alloying method. Furthermore, a die bonding part is improved in electric conductivity and a thermal resistance characteristic for preventing the IC chip from being destroyed due to a latch-up phenomenon, whereby a COG fluorescent character display tube can be assured which is excellent in a stable characteristic thereof.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fluorescent display tube, in which a display portion and a drive circuit portion consisting of a semiconductor element are integrally formed on the same glass substrate, and the display portion and the drive circuit portion are integrally formed on the same glass substrate. A chip on glass, commonly known as a chip on glass, is provided in the same vacuum envelope.
ss) J (hereinafter referred to as COG) structure. .

[Conventional technology]

As a conventional fluorescent display tube having a COG structure, a structure as shown in the partially cutaway perspective view of FIG. 3 and the main part cutaway plan view of FIG. 4 is provided.

In the figure, a plurality of wiring coatings 2. are laminated and deposited on a glass substrate 1. Insulating coating 3. An anode substrate 6 which also serves as a segment electrode 4 and a drive circuit section (hereinafter referred to as a pad section) 5; on this anode substrate, an external lead 7 as an input terminal of a pad section 50; A so-called frame electrode group in which a filament cathode 9 is arranged is placed at an appropriate distance from the integrated grid 8, and furthermore, an IC chip 11 is mounted on the pad portion 5 by a bonding method or the like. The whole is sealed with low melting point glass in a light-transmitting vacuum-tight container (referred to as a cover glass) 10, and electricity is applied to the terminal of the external lead 7 to drive the COG fluorescent display tube via the IC chip 11. A structure that does this is provided.

[・Problem that the invention seeks to solve]

In conventional fluorescent display tubes having such a COG structure, heat-resistant polyimide paste was used to die-bond the IC chip 11 onto the glass substrate.

This polyimide paste is heated to about 450° C. when sealing the cover glass 10. However, this polyimide paste partially begins to decompose at around 430° C., and has problems in that moisture and gas are generated during sealing, and the organic polymer deteriorates. It was also discovered that voids were generated in the polyimide paste during die bonding, and the air trapped in the voids was gradually released during the operation of the fluorescent display tube, adversely affecting the emitter characteristics. . Furthermore, when the chip itself must be connected to VDD or Vss potential depending on the 110 types of IC chips to be mounted, an electrical resistance layer is generated in the die bond layer due to deterioration caused in the previous die bond machine, and the IC chip 11 is connected to the specified voltage. There was something that electric potential couldn't do. In this case, problems such as destruction of the IC chip due to a latch-up phenomenon occur during operation.

[Means for solving problems]

The present invention solves the conventional problems as described above.
The present invention is intended to provide a fluorescent display tube having a G structure. The main point is that the conventional method of using paste (organic or inorganic) for die bonding of the IC chip 11 has been changed to using an Au-Si bonding method. This Au-8t eutectic method has excellent electrical conductivity and a small n1 thermal resistance compared to die bonding using the conventional paste method.

In the present invention, in order to apply the Au-Si eutectic method, for example, a metal support supporting a thin filament wire, which is one of the frame electrode groups, is used as an IC chip.
It is etched into a shape that extends to the mounting part of the l. The diepond part of this metal support is plated with Au,
The u-Si eutectic method is used.

The present invention will be explained in detail below using examples.

〔Example〕

1 and 2 are partially cutaway perspective views showing an embodiment of a fluorescent display tube having a COG structure according to the present invention.

In the figures, the same members as in FIGS. 3 and 4 are designated by the same reference numerals, and their basic roles are no different from those in the conventional method.

In FIG. 1, a segment electrode 4 having a phosphor layer and a pad portion 5 electrically connected to a driving circuit IC chip 11 by a wire bonding method are provided on a glass substrate 1. Here, the IC chip 11 is die-bonded on the metal support 20 for die-bonding according to the present invention by the Au-Si eutectic method. The cover metal of the metal support 20a is etched, and furthermore, Au is applied to the IC chip mounting area.
Plated. Thereafter, it was heated to about 400° C. in an inert gas containing nitrogen, and the IC chip 11 was bonded using the Au-8t eutectic alloy method. A metal support 20 to which the IC chip 11 is bonded is welded to a metal support 30 supporting a filament 9 that is at ground potential in this embodiment.

FIG. 2 shows an example of a shape in which a metal support for supporting filament 9 and a support for die bonding are integrally processed as a second embodiment of the present invention.

In this example, 426 alloy (4:)%N1-ct%Cr-
A metal support 40 that supports both the filament and the IC chip is integrally formed by etching using residual Fe. 426 alloy has a coefficient of expansion close to that of soda glass, which is the material of cover glass-10, and is widely used as a support for fluorescent display tubes. The mounting method for the IC chip 11 is the same as the example shown in Fig. 1 (Au plating is cooled and An-Si eutectic bonding is performed.Although not shown, a gold scrap support is used as shown in Fig. Instead of integrally processing the die bonding support 40, the die bonding support may be separated and formed in the same shape as the external lead 7.

〔Effect of the invention〕

In the uninvented COG fluorescent display blue fabricated in this way, Au-S
By bonding the IC chip using the i-eutectic alloy method, there is no release of gas, moisture, etc. due to polymer decomposition that occurs in conventional organic polyimide pastes, and the electrical conductivity and thermal resistance properties of the bond part are improved. Excellent C with improved characteristics, eliminating IC chip damage due to latch-up phenomenon and stable characteristics even during long-term operation tests.
OG fluorescent display tubes are now available.

Although this embodiment describes a segment type fluorescent display tube, it can also be applied to a graphic type display tube, and can also be applied to connection not only to a filament support but also to other electrode supports. It goes without saying that various selections can be made depending on the characteristics (for example, potential) of the IC to be mounted, and that the invention can be implemented with moderate modifications without changing the gist of the invention.

[Brief explanation of drawings]

1 and 2 are partially cutaway perspective views showing an embodiment of a fluorescent display tube having a COG structure according to the present invention, and FIGS. 3 and 4 are views of a conventional fluorescent display tube having a COG structure. FIG. 2 is a partially cutaway perspective view and a cutaway plan view of essential parts. 1...Glass substrate, 2...Wiring coating,
3... Insulating layer, 4... Segment electrode, 5... Pad portion, 6... Anode substrate,
7... External drawer lead, 8... Grid, 9... Filament shade! , 10...
-...Cover glass (vacuum-tight container), 11...
... IC chip, 20 ... Metal support for die bonding (Au-Si eutectic method), 30 ... Gold, @ support (support for filament etc.) (commonly known as frame electrode group), 40... Metal support in which the above 20 and 30 are integrally formed (Au-Si eutectic method)

Claims (1)

[Claims] 1. A display section having a phosphor layer and a circuit section consisting of a semiconductor chip for driving the display section are integrally formed on the same substrate, and the display section and the circuit section are in the same vacuum envelope. 1. A fluorescent display tube having a structure in which a semiconductor chip forming the circuit portion is die-bonded with an Au-Si eutectic alloy. 2. The firefly according to claim 1, wherein the Au-Si eutectic alloy is formed on a metal support consisting of the same frame electrode group that supports filament electrodes, etc. light display tube.